Those who expected McIlroy to be satisfied or even relieved to secure his best finish at the Majors in a crisis-ridden season severely underestimated the ambition which once again burns deep inside this remarkable 24-year-old.

After a perfunctory few comments to host broadcasters Sky TV and Sirius XM about the final-round 70, which would leave him tied eighth on three-under and seven behind PGA winner Jason Dufner, McIlroy headed straight to the locker room.

Insisting he'd a flight to catch, the Holywood native hurriedly changed into his street shoes and then made for the car, leaving a small pack of newshounds in no doubt about his humour as he smacked his spikes noisily against the door.

This gesture gave better measure to McIlroy's feeling than any words and, in the circumstances, a little anger said a lot about how far he'd come over four fascinating days at Oak Hill.

No doubt, McIlroy made what he described as "a very big step" in the right direction at the PGA Championship. "I saw a lot of great signs out there and hopefully I can bring that through to the next few weeks and have a strong finish to the season," he told TV viewers.

Frustration

Yet his frustration was plain minutes later as he marched across the parking lot. "My game is in great shape ... I'm just a little disappointed I didn't capitalise on the way I played today."

Incidentally, he'll unwind for a couple of days in Cincinnati, where Caroline Wozniacki plays in the Western and Southern Masters, before heading to New York in midweek to begin practising for next week's first FedEx Cup play-off, the Barclays.

Golf is a numbers game and when the figures were added up on Sunday evening, Dufner lay two ahead of Jim Furyk after overturning his US Ryder Cup team-mate's one-stroke overnight lead with a final-round 68.

Both finished with back-to-back bogeys. Yet Dufner's iron play over the other 16 holes had been so impeccably precise, he kept all opponents at arm's length as he sought sweet retribution for his sudden-death defeat against Keegan Bradley at the 2011 PGA in Atlanta.

One suspects McIlroy, not to mention third-placed Henrik Stenson and another of Dufner's closest pursuers, Adam Scott, bristled at their failure to put the 36-year-old under more serious pressure on Sunday.

The winner, who'd afterwards admit feeling "pretty nervous" as he made a three-foot par putt on the first, was given a relatively stress-free ride to his first Major title and third Tour victory in 16 months.

In fairness, Dufner created a comfortable cushion for himself by playing his first eight holes in three-under.

He has gone that low before. McIlroy posted a closing 62 to win at Quail Hollow three years ago and a couple of months later equalled the all-time low round score at the Majors with a 63 of his own on Thursday at the British Open in St Andrews.

Had he emulated Aussie Jason Day and played his first 13 holes on Sunday in six-under, might the feel of hot breath on his neck have affected Dufner's focus?

All this is rendered academic by the treble-bogey seven McIlroy took at five, where, for the second time in four days, his approach from mid-fairway rolled back off the green into the hazard.

"I actually didn't hit a bad shot," he said of that ill-starred nine-iron. "I mean, I'd 168 to the pin, and pitched it in exactly the place you don't want. Had it been a few feet right or a few feet left it would have been fine."

Fair enough, but McIlroy took bogey five after dropping out of the same hazard on Thursday. So the real damage was caused by his next shot, which flew off the green into bottomless rough.

After his fifth held up on the fringe, he took two to get down, wiping out any hope of hanging onto the Wanamaker Trophy. Still, McIlroy doughtily made back those three strokes on the way to the finish, but after four days in which the power of positive thinking once again had been made plain to him, he must have been left with an abrasively nagging thought.

If a simple change of attitude, prompted by a pep-talk from his putting coach Dave Stockton the previous week at Firestone, was so effective in turning his season around, then why in heaven's name had he wallowed for so many months?

Especially when a similar chat with Stockton 12 months earlier inspired McIlroy to burst out of a mini-slump, win the PGA in record-breaking fashion at Kiawah, leap to world No 1 and embark on a breathtaking run which propelled him to the top of the money list in the US and Europe.

Of course, other issues weighed down upon him this year. Like adjusting to his new Nike clubs in the early months of the season, a process complicated by his failure to play enough competitive golf.

In fairness, a timely putting tip from the venerable American also impacted favourably on McIlroy's performance at Oak Hill.

Yet as Stockton candidly said early last week at Oak Hill, in striking a balance in his life as the world's No 1, as a $20m-a-year icon for Nike and a coterie of other sponsors, as a new householder in West Palm Beach and not forgetting his obvious commitment to his relationship with Monaco resident Wozniacki, McIlroy fell behind in his work.

All of this, and even McIlroy's decision this year to walk away from Horizon after 18 months of a five-year management contract, actually is quite trivial alongside some of the grave issues dealt with by colleagues in elite professional golf and other walks of life.

At Firestone, McIlroy's demeanour on the golf course was markedly improved as he played 72 competitive holes for the first time since June's US Open.

When he teed it up at Oak Hill, he looked sharp, birdieing three of his first four holes. He also was resilient enough to come back from a rough patch through the turn (and a 70-minute weather delay) to finish out a satisfying 69.

Looking likely to get washed out of the tournament as he slipped to four-over-par during a Friday morning deluge, McIlroy then fought back with four birdies in six once the downpour stopped. Clearly, he's no longer prepared to let it rain on his parade.

"I'm just being more positive," he'd explain. "It's more about your attitude than anything else and not getting too down on yourself."

With this frame of mind, plus a little anger, to spur him on, it'll come as no surprise if McIlroy gets back to winning ways in the FedEx Cup play-offs. The kid is back!